Proximity sensors are capable of detecting the presence of a target without physical contact. They generally emit electromagnetic radiation, measure the return signal, and identify the location of the target based on the profile of the return signal. Proximity sensors are commonly used on mobile devices such as smartphones to detect accidental touchscreen taps when held to the ear during a call. Portable devices such as wristwatches may also include a proximity sensor that detects whether the watch is “off wrist” and should be turned to a locked state. However, for those users who prefer to wear their watch loosely against their wrist, such a proximity sensor may cause unintentional locking of the watch, or other consequences.
Accordingly, it may be beneficial to develop alternate methods or devices to more accurately determine the location of a wearable device relative to the user.